It is known to provide an irrigation system with a timer which controls valves to deliver irrigation water at preselected times and controlled rates to fields. The term "irrigation" includes the supply of water through open trenches, through conduitry to supply them, to sprinkler systems and drip systems, and generally to all types of flow in which the time and duration of water supply, and the amount and time of injection of additives is a feature. The total volume of water is controlled by setting the on and off times of the timer controlling the particular valve. Timers which can selectively control and operate several sprinkler or irrigation systems are known for remotely controlling the on and off times of a plurality of valves selectively to irrigate different areas or fields at different times, because the available water capacity and pressure usually only allows irrigation through a limited number of outlets at any one time. Thus, to cover a large area, staggered irrigation times for selected areas are often required. Also, mobile systems sprinkle regions of varying shapes and areas, so that a mere off-on timer can not be expected to respond to its needs.
Agricultural chemicals are frequently applied separately from the main irrigation stream by machines or aircraft because of the limitations of the irrigation art. Presently, irrigation water cannot effectively be used as the carrier, even though important benefits are potentially available from such delivery. Examples of such benefits are reduction in the amount of chemicals needed, better utility of what is applied, reduction of labor costs, and certainty of the results.
Even more, some additives are not compatible for simultaneous mixing with other additives in the irrigation water. It is then necessary separately to inject these compounds. This is at the best a nuisance. It is evident that a time clock is an unsuitably simple device to control what is inherently a sophisticated application of chemicals, many of which represent hazards if applied in the wrong concentration or at the wrong time. For example, the supply of chemicals into the system when it is not in a flowing situation which will give an immediate slug of chemicals when the system is again opened to flow. Still, timers which relate to the day and to the time of day are an important and prevailing working tool for the agricultural industry.
An object of this invention is to provide an automatic controller for fertilizers and chemicals which operates in tandem with and is an adjunct to a basic irrigation timer. Since optimum injection of chemicals is directly related to the timing of the flow of water, the present invention relies upon and reads the valve-opening signals of the irrigation timer as input data and is programmed to activate injection only when a predetermined valve opening signal is recognized, and to close it otherwise.
The invention is also programmed to terminate a programmed injection event any time there is a malfunction of the basic irrigation timer or an identifiable failure of the irrigation distribution system or of the injection device.
Yet another object of the present invention is to provide a totally automated irrigation system for injecting additives into irrigation water which is programmable to control a number of injection devices sequentially, all at once or in any desired combination thereof.
The automated irrigation injection system of this invention controls the operation of relays to operate valves at selected times while simultaneously operating valves to inject additives into the flow of irrigation water (or not to do so if the program calls for it).
An additional object of the present invention is to react to supplementary signal to terminate the injection of additives upon the sensing of parameters such as loss of flow or low pressure. This system will still retain in its memory the pre-programmed schedule, and will resume operation after the problem which caused termination has been corrected. This system also permits manual termination of the injection of additives at any time.